Add support for vkCmdCopyBuffer

This is then used when need to update GPU only buffers with data of size
greater than 65536. We create a temporary transfer buffer and then copy
that buffer into our GPU buffer.

Bug: skia:
Change-Id: I4bb9cb660f2ac1ccbbd1b508bb4ca6876342136f
Reviewed-on: https://skia-review.googlesource.com/38725
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
6 files changed